[Elecraft] K3: Added protection for RS-232 port (summary)

[Pete Smith]

Thanks to the Elecrafters who responded with a raft of good ideas.  That 
included W8JI, W4TV, K9YC, W9AC, N7MG, NN4X, KX4O, W3FPR, and AI4VZ 
(more or less in the order in which they responded.  I hope I have 
understood and can render all the input correctly

Consensus seems to be that grounding, particularly making sure that all 
chassis are bonded together with the station entry panel and the 
powerline ground, is the best protection.  I think this likely is where 
I went wrong, because I had just completed the radio and had not yet 
grounded it to my station bus, which is 3/4" copper pipe behind the 
radios, wired to the station entry panel with heavy copper.  As I write 
this I'm in the midst of going through my station to make sure that 
everything is properly grounded.

Several people provided ideas for component level protection, but W9AC 
found the Tripp-Lite DB9, which is a nicely packaged in-line protector 
that (they say) use "balanced arrays of high-speed avalanche diodes" to 
shunt the energy to ground.  At $20 including shipping (Newegg was the 
cheapest I found) it can't hurt.  I probably couldn't build it that 
cheaply, and it might help, particularly in combination with the 
grounding improvements.

-- 
73, Pete N4ZR

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